refleak.py reports spurious leaks due to int allocation

[nascheme]

Bug report

Bug description:

The refleak checker in Lib/test/libregrtest/refleak.py can pollute its own reference-count measurements and report a spurious leak. The int_pool structure is pre-populated only for common values between approximately -1000 and 1000. When memory-block deltas are large and unique, each repetition inserts a new integer into the pool. The refleak checker should not create Python objects that affect subsequent reference-count or allocated-block measurements.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-155981: Store refleak deltas in arrays #155982